When Horst Koehler became the first non-politician to be elected German president in 2004, one newspaper ran a headline which read, "Horst Who?"

When the former International Monetary Fund (IMF) boss castigated financial markets as a "monster that must be tamed," tabloids dubbed him "Super-Horst".

But after his shock resignation just one year into a second term, the question in the German media now is: "Horst, why?"

Chancellor Angela Merkel said she was surprised when Mr Koehler phoned her just two hours before stepping down. She tried to change his mind, but failed. So she paid tribute to a popular president who "had won over people's hearts".

But the "people's president" had come under fire for his comments linking military action abroad with the defence of German economic interests, such as securing free trade routes.

It did not help that many of Mr Koehler's long-term advisers, including his experienced spokesman, had recently left, apparently disgruntled.

Ironically, a new spokeswoman was to begin work on Tuesday.

'Emotional manner'

In his emotional good-bye message, the president insisted he had been misunderstood.

Although he gave the controversial interview on his return from a surprise visit to Afghanistan, his office said Mr Koehler was actually referring to Germany's involvement in the EU anti-piracy mission off the Somali coast.

Image caption
One German newspaper called Mr Koehler's resignation "irresponsible"

Last Friday, all three opposition parties asked for clarification.

The defence minister distanced himself from the statement, while Mrs Merkel said nothing to back the president.

Germany is the third biggest troop contributor to Afghanistan, but the mission remains deeply unpopular.

For historical and constitutional reasons, German politicians shy away from even calling the Afghan conflict a war.

Reopening the debate over Afghanistan proved an embarrassment to the centre-right coalition, just as its popularity slumped to a four-year low in the polls over the management - or mismanagement - of the euro crisis.

The leading German tabloid Bild called the resignation "irresponsible".

The centre-right Frankfurter Allgemeine Zeitung described Mr Koehler as a "tragic figure".

The centre-left Sueddeutsche Zeitung said nobody had ever damaged the presidential office to such an extent, while the left-wing Tageszeitung said Mr Koehler had behaved in an "emotional, almost unpolitical" manner.

Bad timing

The president's role is largely ceremonial, but Mr Koehler was the candidate of the centre-right and his resignation has come at the worst possible time for Mrs Merkel.

It heightened the sense of drift and added to the chancellor's already long list of problems.

Over the next month, she has to find a suitable replacement, help save the euro, and make deep budget cuts.

The speaker of the upper chamber of parliament, the Bundesrat, has stepped in temporarily as president.

Mr Koehler's successor will be elected on 30 June by a federal assembly of more than 1,000 people, including the members of the lower chamber of parliament, the Bundestag, and representatives of Germany's 16 federal states.

While Mrs Merkel's coalition has the majority in the federal assembly, she will try to get the opposition's support for a president who can keep above the political fray.

Possible contenders are the finance minister, Wolfgang Schaeuble, and the prime minister of North Rhine-Westphalia, Juergen Ruettgers.

Several women are also in the running - education minister Annette Schavan, labour minister Ursula van der Leyen and Margot Kaessmann, who resigned as the head of Germany's Protestant Church earlier this year after being caught drink-driving.

But only minutes after Horst Koehler announced his resignation, the internet was full of tongue-in-cheek comments suggesting that the most popular candidate for president would be Lena, the 19-year-old school student who has just won the Eurovision song contest.